I highly recommend Steel Beasts. I was an avid player for many years. The price to own it might seem high at first, but there are many options which allow you to try it for a limited time at very little cost. (E.g.: US$9.50 for 1 month.)

It is a sim, and you can spend days learning what each switch does in a particular vehicle. (It is actually used by [IIRC] nine different armies to train their tank crews.) However, you can also play it exclusively from the map screen and just direct your units where to go and let the AI do all the dirty work, or even script out the movements in the planning phase before the mission starts and sit back and watch it unfold. Or anywhere in-between. There are quite a few missions included and at least one campaign, and there are many more missions available for download on the forum site. The mission editor is extremely powerful and allows for randomization such that even the designer of a mission might not know exactly what to expect, and makes replay-ability very high.

The graphics aren't the best (the game is over fifteen years old now), but the devs have spent a great deal of effort making sure the physics are accurate. And there are constant updates improving everything from features to graphics. There is a huge number of vehicles to choose from, most of which can be crewed by the player. I think all are post WWII. There is no DLC in terms of weapons or vehicles, you get everything up-front and everyone is on a level playing field. The only advantage comes down to skill and tactics.

There are no dedicated servers. Each online game must be coordinated in advance with one player acting as the host, but there is a community game every Friday night at 10 p.m. EST and many "virtual units" which meet regularly and welcome newcomers. The online community is second to none (many RL current and ex-tankers) and the members will gladly help any noobs learn the ins and outs. It's relatively easy to learn the basics, but mastering the strategy may take a lifetime. Occasionally, there will be an online campaign lasting several weeks.

IMHO, when it comes to tanks: there is no equal to Steel Beasts. The devs are totally engaged with the community and regularly post in the forums and respond to civilian requests for in-game content whenever they can. (Although their military customers do take top priority.)

Feel free to ask me any questions you may have about it. There are also plenty of videos on YouTube. Here is one I made of an online campaign I played in a few years ago: